Efficacy Study of Nifedipine Controlled-Release Tablets (Xin Ran) to Treat Mild to Moderate Essential Hypertension

Inclusion Criteria: * Voluntarily participate and must sign informed consent form * Mild to moderate essential hypertension (SBP 140-179 mmHg and/or DBP 90-109 mmHg) * Average DBP measured by 24-hour ambulatory blood pressure monitoring (ABPM) ≥80 mmHg Exclusion Criteria: * Secondary hypertension and malignant hypertension * Pregnant or nursing women, or patients that cannot guarantee to take effective contraception measures * Baseline SBP≥180 mmHg or DBP≥110 mmHg, or patients with cerebral, cardiac or renal complications * Have following complications: cerebrovascular accident within 6 months, myocardial infarction or cardiac failure, macroaneurysm or dissecting aneurysm, definite angina, A-V block of grade 2 or higher, sick sinus syndrome, atrial fibrillation or other malignant arrhythmia * Clinical significant diseases of heart, lung, liver, kidney and hematologic system or malignant tumors, HIV infection, uncontrolled diabetes (fasting blood glucose ≥7.0 mmol/L, 2-hour postprandial blood glucose ≥7.8 mmol/L) * Kock pouch * Sever gastrointestinal stenosis * Abnormal laboratory values with clinical significance, including serum potassium \<3.5 or \>5.5 mmol/L, glutamic-pyruvic transaminase (ALT) or glutamic oxalacetic transaminase (AST) \>2-fold upper limit of normal (ULN), Cr \>ULN * Uric acid \>ULN with the diagnosis of gout * Gastrointestinal abnormalities or surgery that may interfere with drug absorption * Hyperthyroidism or hypothyroidism * Allergic to any ingredient or metabolite of investigational drug or drugs of similar structure * Heavy smokers (\>25 cigarettes every day), alcoholics (\>250 ml liquor every day), drug addicts * Psychological diseases, acrasia, cannot express explicitly * Patients whose mood may be affected by variations in blood pressure, which in turn increases blood pressure * Anxiety disorders, depression or cannot follow study protocol * BMI \>30 * Night shift, irregular sleep patterns or insomnia * participate in other clinical trials within 3 months * other conditions that investigators consider unsuitable for participation